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Investors Fund US $10.75 M for Honolulu Seawater Air Conditioning

By Peter Myers
July 9, 2008   |   12 Comments

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12 Reader Comments
Comment
1 of 12
July 9, 2008
The Honolulu project site claims that it saves about 80% of the energy compared to a standard chiller with air-side heat rejection system. Perhaps reality is less than that, but still the savings are impressive. If the economics work (you're sitting next to deep cold water, you can afford a huge up-front investment, etc) it's worth doing. However, it's not completely isolated from power rate increases; it's just more energy efficient.

The other problem is that the straight-through heat exchanger probably puts out a chilled water supply temperature to the building of about 48F. That's pretty marginal (a typical standard is 42F) for cooling, unless you have nice gentle summers, such as Hawaii, Ithaca, or Stockholm. This might be practical in the San Francisco Bay Area, less so in LA.
Comment
2 of 12
July 9, 2008
I wonder what the energy requirements of pumping the water are compared to that of conventional air conditioning and compared to conventional geothermal heat pumps. Anybody know?
Comment
3 of 12
July 10, 2008
Ok energy check, what about the ocean itself with all the living organisms and ecosystems. I fear construction in any form, especially around coast lines. Runoff is inevitable and has been going on in Hawaii for years, in addition to the slow decay of coral. But whatever, I don't have millions; therefore, I can't talk, only on the bottom of comment pages........live on.
Comment
4 of 12
The 48F is the Hawaiin deep water temperature. The temp in LA may be colder making it a viable option there as well.
Comment
5 of 12
July 10, 2008
I believe that they are going to use a double loop heat exchange system so that fresh water and not cold salt water would be used in the pipes going to the buildings. This system should prevent corrosion of the pipes.

Since such a high percent of all electricity in Hawaii is presently generated by burning fossil fuels (mostly sour or high sulfur oil from Indonesia), good savings should result.

adrianakau2aol.com
Comment
6 of 12
July 11, 2008
Since you are pumping large amounts of water from the deep why not combine this project with an OTEC 'spar'? If not for grid power then perhaps generate only enough to do the air conditioning pumping. One problem with OTEC is the proximity of the differential temp. water to population needing electricity; in this case you need the power right where you are pumping cold water to begin with.
Comment
7 of 12
July 11, 2008
Cold water from the deep ocean is very clean in terms of pollution and the larvae of pipe fouling organisms and is usually nutrient rich. This raises the possibility of letting the water out into shallow ponds or even an impounded bay, sometimes with a little silicate added to encourage diatoms, and then passing the water through 3D oyster beds. The Pacific oyster can be brought to a large commercial size in 8 or 9 months. Why waste this water by diffusing it back into the ocean. Get another product out of it.

Another wrinkle if this system catches on world wide. Such a system, would start to lower the level of the thermocline. If you don't think it is possible, look at other effects man has had on his environment. Who would have thought we could destroy the Amazon rain forest or cut away large mountains for their minerals. As the thermocline lowers, clatrates will start to release their methane. Could be interesting.
Comment
8 of 12
July 11, 2008
The article notes a January '09 start-up date and that they will now begin the environmental impact statement (EIS). The EIS process takes at the very minimum one year, assuming no significant controversy. This technology appears to have tremendous potential, but I often wonder about the credibility of press releases. Does anyone know who will be the federal lead agency for the EIS- DOI/MMS or FERC? FERC has asserted jurisdiction over wave energy projects, thereby conveying EIS lead status and regulatory authority. Hawaii's Coastal Zone Management Act (HCZMA) will have to be followed as well. I am confident environmental impacts can be minimized if project construction is approached sensibly and with the sensitivity to protect Hawaii's valuable coastal and marine resources. Hawaii has tremendous potential with renewables, many of which the Hawaii Renewable Energy Lab has studied. We now have rapidly advancing technologies spurred by rising oil prices, which are opening up a world of opportunities. Seems like lots of expertise out there judging from above comments.
Comment
9 of 12
July 11, 2008
This project sounds very familiar to the experimental Ocean Thermal Energy Technology (OTEC) projects of the early 1980's. The enemy of OTEC is marine fouling and salt water corrosion. I helped build an experimental 50 kW OTEC plant on top of a 60 x 160 ft. barge. It produced 50 kW total, but needed 40 kW to run the pumps, therefore netting only 10 kW. I saw this barge sitting next to the pier years later, and it was totally corroded in ~only two years of operation.
Comment
10 of 12
July 11, 2008
I agree with Muir Matteson. The buildings ARE going to be cooled, so they might as well use a local resource, rather than tankers bringing oil across that same ocean.
Comment
11 of 12
July 11, 2008
Pumping the seawater around shouldn't take a great deal of energy. It may be coming from 1600 feet down, but it doesn't have to be LIFTED 1600 feet, as water might have to be lifted from the depths of a well in the desert. The seawater enters the pipe with all the pressure of the water above it, so the pumps have to do no more work than if the pipe were horizontal and on the surface. This is a very small pumping job. The heat exchanger, with a large number of narrow openings, presents a bit of friction. Even so, it probably still requires only a tenth the electricity of a conventional air conditioning setup.

Regarding the underwater environmental impact, it's really not huge. Look at the overall picture. The project has some impact, yes. But look at the impact it prevents. It keeps a lot of fossil fuels from being burned on Oahu. So, there will be less ships crossing the ocean, less chance of oil spills, less air pollution, less runoff. On the whole, a big positive.
Comment
12 of 12
July 12, 2008
It sounds like a good idea. I'm surprised it took this long. They could line the saline section of piping with a glass if corrosion is a problem, but I'm sure they have thought of an obvious thing like salt water corrosion before spending all this money.
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